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This is a discussion on Race Compound Shoes within the Technical forums, part of the Caferacer.net Forums category; Hmmm... I thought you said you'd arc'd those with the hub. I think it's really strange wear, but extra eyes would be good. I've got ...

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  1. #11
    Senior Member RookieGeorge's Avatar
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    Hmmm... I thought you said you'd arc'd those with the hub. I think it's really strange wear, but extra eyes would be good. I've got to get those photos.

    I just can't get my head around the dynamic geometry somehow. I wish I had a streeter I could use for experimenting.
    USCRA #113 FCB fodder

  2. #12
    Moderator jbranson's Avatar
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    George, how much have you used them, and how hard?

    Next question would be how you installed the wheel. With forks using and axle clamp you have to tighten the axle with the brake applied by hand BEFORE it is installed into the forks.
    On bikes with "through the forks" axle you install the wheel first, then tighten the axle while applying the brakes firmly.

    This process aligns the shoes and hub, and as you tighten the axle it locks it in place. If you don't do it this way it axle will torque the hub and shoes out of alignment.

    I arc all the shoes/brakes that I send out, and do the initial linkage adjustment with an axle slide through the hub. But...It's not on a bike, problems with an axle, or fork alignment etc. can throw the whole thing off.

    In a less than ideal situation you'd have to adjust the shoes by sanding. Send some pics if you get a chance. To my email if you still have it.

    Also...those short levers....way too little force for a race brake. You gotta have some good leverage at the lever. How many races do you have on it? Vesrah are going to take some time to bed in...they are designed to last a long time...not necessary stop real well. Race shoes sacrafice themselves for braking power, so they bed in quicker.

    Check your axle for a bend too, check that spacers are flat and square. What works on the bench doesn't always work on a bike, depends on how "right" the bike is.
    JohnnyB

  3. #13
    Senior Member ttilghman's Avatar
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    johnny-

    so your hub and shoes are spot on. the contact area is huge, from front to back on both shoes with just a little difference at the corners of the trailing edges. i did find another broken spring and a little gouge (maybe the shrapnel or hanging spring) on the taper of the leading edge of the lower shoe. it seemed it would be below the contact surface, but i smoothed it out anyway. and as to my spongieness, i can see a litte expansion in the cable braid, at the lever, when at rest, so it's obvious now that i need a new cable. who's cables do you like?

    thanks again.
    -tt

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  5. #14
    Moderator jbranson's Avatar
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    TT,
    Motion Pro makes a good cable if they have them for that brake...order one to match the hub, so 305 for 305 etc. Although I don't think there is any cable difference in the 450. As heavy duty as you can get.

    Another broken spring? That's weird...they move so very little on a brake like yours. I'm having trouble finding good springs, most of them are too rusty. Keep your eyes open for NOS stuff. At some time I might have to look into having some made. Or finding something later model still made that will work.

    Typically there will always be a tad of dead contact space towards the pivot until you really get some laps on them.
    JohnnyB

  6. #15
    Senior Member RookieGeorge's Avatar
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    The wheel installation is a component I didn't have any control over since the shop reworked my axle at the last minute. There's a very good chance that was a factor. I'll proceed as advised on re-installation. I noticed there is a ton of play in the brake / hub interface.

    The pads hardly have any break-in. I had 2 practices and two laps when I went down. They've got lots more breaking in to do. I got some photos, finally. They're up here: http://smg.photobucket.com/albums/v3...oy/Cycletrips/
    USCRA #113 FCB fodder

  7. #16
    Moderator jbranson's Avatar
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    George,
    Hmmm....what kind of shop did the work? Was it a vintage shop? If not they probably have no idea how to install a drum brake. What did they do to the axle....the axle is a major factor as it is what holds the alignment between the hub and brake plate. Looks like the whole brake plate is offset in one direction in the hub. Very unusual to see all the braking on ONE side of the plate at a pivot/cam area. Usually you'd see wear at both cams, or wear at both pivots if arc is wrong.

    Do you think the shop removed the shoes for any reason? If so they might have put then in backwards (top on bottom, bottom on top).

    Things like spacers are very important...if the ends of the spacers are not lathe turned square (perpendicular to the axis of the axle) when you tighten the axle it tries to cock the brake/axle sideways. Spacers cut with a hack saw etc will not be square enough.

    When I build a race brake the tolerances are much closer than on a street brake....this requires that the installation be much more precise because now small errors will have a large effect on how the brake works.

    I'm guessing when you apply the brake you see that "play" as the brake plate trying to move separately from the hub.... this is because the two are not aligned. The process of applying the brake BEFORE tightening the axle holds the plate and the hub in alignment....then when the axle is tightend it locks it in place....so you don't have the movement....cause it's already where it wants to be....if you take my meaning.

    If this is not done then every time you pull the brake lever it's trying to bend the axle and bring everything in alignment...which it can't do of course. Your lever has got to be all kinds of spongy.

    Typically I label the shoes top and bottom. Make sure that's right first. Although I know there have been sets I didn't label. I actually label them for myself as I have a special plate I use on the lathe for turning the shoes and then transfer them to the customers plate.

    And by top and bottom shoe I mean the top shoe is the one that is toward the top of the bike, and vice versa....it doesn't mean what is facing up and what is facing down as you look at the plate on a bench.

    That big movement between the plate and the hub is almost without question the problem, and that movement is indicative of a mis-alignment during installation. Believe it or not...despite the fact that these are old, primitive bikes, things like the brake have to be quite precise to work properly in a race scenario. There are very few shops outside a vintage race bike shop that will have any idea how to set it up properly. You'd do a better job at your house with some care and instruction.
    JohnnyB

  8. #17
    Moderator imslow's Avatar
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    hey george when the heck did you re-paint my bike? Remember, I want it back if you ever decide to sell . . . .

    Inertial dynos just make people cranky

  9. #18
    Senior Member RookieGeorge's Avatar
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    Evil - It's a Tannermatic tank and fender - no repainting.

    It was The Motorcycle Shop that did the work, so I expect the work is at least competent. They had to cut spacers to mate the 550 forks, 750 triple, and 77 hub. I'll check square on those first and check the axle for straight. They had no reason to touch the pads, but I'll check those too.

    I don't recall loosening the axle from the wheel last year, but I know I loosened the axle from forks (to drill the nuts) after the shop had the bike. It's likely the "squeeze, tighten" protocol was not followed somewhere along the line - probably by me in my ignorance. I'll have to see how much motion I get in the kit when I get it all reinstalled - hopefully Sunday.

    Thanks for the feedback.
    USCRA #113 FCB fodder

  10. #19
    Moderator jbranson's Avatar
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    If you are using 550 forks...that's the same as I use. The process is kind of a pain in the ass.

    With the wheel off the bike you take something like a quick clamp and put one end on the brake arm, the other on the cable stay and tighten the clamp to imitate the cable applying pressure. Not so much you break something...but considerable pressure. While this clamp is in place you put the axle through, along with any spacers needed and tighten the axle.

    The 550 forks are VERY particular about spacers...the way the axle is setup the axle nut has to fit perfectly aligned in the clamp, if you have to tweak the forks even a tiny bit to get the axle to seat in the clamps then it's not right.

    When you slide the wheel under the forks and lower the bike...the axle should fit right up into the clamps with NO drama. The shouldered axle nut should slip right into the clamp.

    After the wheel is installed...you should never screw with the axle with the wheel in the bike...unlike a lot of bikes, the wheel/axle setup on a 550 is a whole separate package from the fork legs.
    JohnnyB

  11. #20
    Senior Member parks61's Avatar
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    johnny's speaking a lot of truth on the (drum) brakes. i'll just add a couple of my thoughts. first, cables aren't usually the sponge culprit...the casing/housing is (along with the ferells etc. as johnny wrote) crappy casing compresses due to a sloppy wind. teflon lining, which is popular, adds to this although i use it on my racer. and i am a firm believer in arcing the shoes on the brake plate which compensates for many of the manufacturing flaws present in most bikes...especially spanish tacos from the sixties. when i did it last, i made a gismo which loaded out the shoes a bit, turned them to the i.d. of my drum, and had super brakes first time out. they wore/ were contacting from leading to trailing edge on both shoes. re-read jb.s hints too.
    -parks
    I\'m not handsome

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